This invention relates to an electrical contact which is for use in an electrical connector of a surface mounting type directly mounted on an electrical circuit board and which is integrally formed from a metal sheet of a conductive plate, and a method of manufacturing the same.
A conventional electrical contact of the type described comprises a pin contact portion at its top end, a press-fit portion extending from the pin contact portion, and a terminal portion extending from the press-fit portion in a backward direction to form a substantially L shape.
All these portions are integrally formed. The press-fit portion is press-fitted into an insulator for the electrical connector. The terminal portion has a top end connected to a conductive pad formed on the electrical circuit board by soldering. The pin contact portion is fitted to and contacted with an electrical socket contact of a mating connector.
Such electrical contact is manufactured in the manner which will presently be described. At first, a single metal sheet having a predetermined thickness is punched to form a contact blank having a temporary shape including a temporary pin contact portion, a press-fit portion, and a temporary terminal portion. The temporary pin contact portion is then shaped into the pin contact portion of a pin shape having a substantially circular cross section. The temporary terminal portion extending therefrom is press-formed to have a thickness smaller than the diameter of the pin contact portion. Thereafter, the temporary terminal portion is subjected to a bending process to form the terminal portion having a substantially L shape.
In the electrical contact thus manufactured, it is assumed that a longitudinal direction of the pin contact portion and the press-fit portion is defined as a X direction. The terminal portion comprises a leg portion extending in a Z direction perpendicular to the X direction, and a foot portion bent from the leg portion and extending in the X direction. The leg portion defines a height with respect to the pin contact portion. The foot portion serves as a connecting portion to be connected to the conductive pad formed on the electrical circuit board. Generally, the thickness of the press-fit portion is substantially equal to or slightly greater than the diameter of the pin contact portion. In many cases, the thickness of the press-fit portion is equal to that of the metal sheet.
In the conventional electrical contact, the thicknesses of the pin contact portion and the press-fit portion in the Z direction are substantially equal to that of the metal sheet from which the contact blank is punched out. On the other hand, the widths of the press-fit portion and the terminal portion in a Y direction perpendicular to an X-Z plane are greater than the thickness of the metal sheet in order to assure a mechanical strength during a press-fitting operation.
With this structure, when a plurality of the electrical contacts are fitted into an insulator of the electrical connector to be arranged adjacent to one another, an alignment pitch of the adjacent electrical contacts can not be made smaller than the widths of the press-fit portion and the terminal portion. This inevitably restricts the density of the electrical contacts. Thus, the electrical connector comprising a plurality of the electrical contacts fitted into the insulator is inhibited from increasing the density of the electrical contacts.
As described, the height of the pin contact portion in the Z direction is defined by the leg portion of the terminal portion. Since the leg portion and the foot portion of the terminal portion are formed by the bending process, a constant working accuracy is difficult to obtain. Again, in such an electrical connector comprising a plurality of the electrical contacts fitted into the insulator, the height at the pin contact portion of each electrical contact often suffers a dimensional error. In addition, soldering of the foot portion (connecting portion) of the terminal portion and the conductive portion (such as the conductive pad) of the electrical circuit board is often incomplete.